crt.sh
Operator: Sectigo Limited
Public search of Certificate Transparency logs by domains, organisations and certificates.
Technical Infrastructure
Product
crt.sh
Availability and source date
Active
As of: 16 October 2026.
No functionality test has been performed.
Use in OSINT research
Helps discover additional hostnames and historical certificate links to a domain. A certificate match establishes neither an active website nor current control by the same organisation.
Queries
| Input | Result | Result type |
|---|---|---|
| Domain / website | Certificates with matching domain names or DNS identities. | Retrieved |
| Company / organisation name | Certificates with a matching organisation name in the certificate. | Retrieved |
| File hash | Certificate with a matching SHA-1 or SHA-256 fingerprint. | Retrieved |
| Email address | Certificates with a matching email or IP identity. | Retrieved |
| IP address | Certificates with a matching email or IP identity. | Retrieved |
Features
- Find TLS certificates by domain or organisation names.
- Search for certificates by SHA-1/SHA-256 fingerprints and other certificate attributes.
- Filter out expired certificates and combine certificate/precertificate pairs.
- Search specifically for certificate identities such as DNS names, email addresses and IP addresses.
Categories
- Technical Infrastructure
- Certificates
Coverage
Dataset
Certificates and precertificates from public Certificate Transparency logs, including expired or revoked certificates.
Access
Requirements
Public web search without signing in. No infrastructure of your own is needed to use the website.
Export
Web view; JSON output is discussed in the project forum. The operator also describes public PostgreSQL access.
Provider
Sectigo Limited
Country of establishment
Unknown
Interfaces
API
Available. Public PostgreSQL data access is described by the operator. JSON endpoints are discussed in the forum; guaranteed API availability is not substantiated.
MCP
Not documented. Not described on the product pages and guides reviewed.
AI agents
Not documented. Not described on the product pages and guides reviewed.
Maintenance
Licence
GNU GPL-3.0 (database code)
Latest activity
Commit 09/2026
Stars
252 (as of 16 October 2026)
Legal note
Limitations
- The search covers published certificates, not all domains or servers.
- Certificate data may be out of date; a domain name in a certificate does not prove that a website is currently active or associated with an organisation.
- The operator has described overload and outages. Only the interface was checked in the current review.
Guides and practical reports
Official · Sectigo: what crt.sh shows
Tim Callan und Jason Soroko · 04/2022 · EN
Official introduction to Certificate Transparency and certificate search.